{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/101227"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/101227","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Effect of network structure on lignin-derived polyurethane film properties","abstract":"Thermosetting polyurethane films were prepared from solution by crosslinking hydroxypropyl lignin derivatives with diisocyanates. The network structure, characterized by the crosslink density, was controlled by two variables: the hydroxy content of the lignin polyol and the molar ratio of NCO:OH. In addition, the effect of network structure on thermal and viscoelastic properties was determined. Both the thermal and viscoelastic properties of the polyurethane films followed the trends found for crosslink density. For those films prepared from the various polyols with reduced hydroxy functionality, T<sub>g</sub> was found to vary linearly with the extent of crosslinking as well as with the T<sub>g</sub> of the polyol from which it was prepared. As the NCO:OH ratio was increased, the major difference in T<sub>g</sub> occurred within the range from 1:1 to 3:1. Similar trends were noted for the viscoelastic properties in both instances. However, it was apparent that the sol fraction contributed significantly to the overall properties of the network, particularly at the high weight fractions. Fracture surface analysis of model substrates (cellulose acetate and cellulose tri-acetate) bonded with a lignin-polyisocyanate resin by Electron Spectroscopy for Chemical Analysis (ESCA) revealed the formation of interfacial bonds on the surface of the cellulose acetate adherend. Furthermore, it was indicated that failure occurred well within the bulk of the cellulose acetate while interfacial failure was apparent for the cellulose tri-acetate model. While mechanical attachment is unquestionably a contributing mechanism, the formation of interfacial bonds should significantly contribute to the performance of bonded joints for this particular adhesive system.","abstract_html":"Thermosetting polyurethane films were prepared from solution by crosslinking hydroxypropyl lignin derivatives with diisocyanates. The network structure, characterized by the crosslink density, was controlled by two variables: the hydroxy content of the lignin polyol and the molar ratio of NCO:OH. In addition, the effect of network structure on thermal and viscoelastic properties was determined. Both the thermal and viscoelastic properties of the polyurethane films followed the trends found for crosslink density. For those films prepared from the various polyols with reduced hydroxy functionality, T&lt;sub&gt;g&lt;/sub&gt; was found to vary linearly with the extent of crosslinking as well as with the T&lt;sub&gt;g&lt;/sub&gt; of the polyol from which it was prepared. As the NCO:OH ratio was increased, the major difference in T&lt;sub&gt;g&lt;/sub&gt; occurred within the range from 1:1 to 3:1. Similar trends were noted for the viscoelastic properties in both instances. However, it was apparent that the sol fraction contributed significantly to the overall properties of the network, particularly at the high weight fractions. Fracture surface analysis of model substrates (cellulose acetate and cellulose tri-acetate) bonded with a lignin-polyisocyanate resin by Electron Spectroscopy for Chemical Analysis (ESCA) revealed the formation of interfacial bonds on the surface of the cellulose acetate adherend. Furthermore, it was indicated that failure occurred well within the bulk of the cellulose acetate while interfacial failure was apparent for the cellulose tri-acetate model. While mechanical attachment is unquestionably a contributing mechanism, the formation of interfacial bonds should significantly contribute to the performance of bonded joints for this particular adhesive system.","abstract_has_math":false,"creators":["Rials, Timothy Gardner"],"institution":"Virginia Polytechnic Institute and State University","degree_name":"M.S.","degree_level":"masters","degree_discipline":"Forest Products","degree_department":"Forest Products","school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1983,"date_issued":"1983","date_published":"1983","updated_at":"2026-07-22T22:19:35Z","subjects":[],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/10919/101227","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.department","label":"Department","values":["Forest Products"]},{"key":"dc:creator","label":"Author","values":["Rials, Timothy Gardner"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2020-12-14T16:34:54Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2020-12-14T16:34:54Z"]},{"key":"dc:date.issued","label":"Date","values":["1983"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Polytechnic Institute and State University"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.dcmitype","label":"Dc Type Dcmitype","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Forest Products"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/101227"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Thermosetting polyurethane films were prepared from solution by crosslinking hydroxypropyl lignin derivatives with diisocyanates. The network structure, characterized by the crosslink density, was controlled by two variables: the hydroxy content of the lignin polyol and the molar ratio of NCO:OH. In addition, the effect of network structure on thermal and viscoelastic properties was determined. Both the thermal and viscoelastic properties of the polyurethane films followed the trends found for crosslink density. For those films prepared from the various polyols with reduced hydroxy functionality, T<sub>g</sub> was found to vary linearly with the extent of crosslinking as well as with the T<sub>g</sub> of the polyol from which it was prepared. As the NCO:OH ratio was increased, the major difference in T<sub>g</sub> occurred within the range from 1:1 to 3:1. Similar trends were noted for the viscoelastic properties in both instances. However, it was apparent that the sol fraction contributed significantly to the overall properties of the network, particularly at the high weight fractions. Fracture surface analysis of model substrates (cellulose acetate and cellulose tri-acetate) bonded with a lignin-polyisocyanate resin by Electron Spectroscopy for Chemical Analysis (ESCA) revealed the formation of interfacial bonds on the surface of the cellulose acetate adherend. Furthermore, it was indicated that failure occurred well within the bulk of the cellulose acetate while interfacial failure was apparent for the cellulose tri-acetate model. While mechanical attachment is unquestionably a contributing mechanism, the formation of interfacial bonds should significantly contribute to the performance of bonded joints for this particular adhesive system."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["M.S."]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Effect of network structure on lignin-derived polyurethane film properties"]}]}],"canonical_facts":{"dc:contributor.department":["Forest Products"],"dc:creator":["Rials, Timothy Gardner"],"dc:date.accessioned":["2020-12-14T16:34:54Z"],"dc:date.available":["2020-12-14T16:34:54Z"],"dc:date.issued":["1983"],"dc:description.abstract":["Thermosetting polyurethane films were prepared from solution by crosslinking hydroxypropyl lignin derivatives with diisocyanates. The network structure, characterized by the crosslink density, was controlled by two variables: the hydroxy content of the lignin polyol and the molar ratio of NCO:OH. In addition, the effect of network structure on thermal and viscoelastic properties was determined. Both the thermal and viscoelastic properties of the polyurethane films followed the trends found for crosslink density. For those films prepared from the various polyols with reduced hydroxy functionality, T<sub>g</sub> was found to vary linearly with the extent of crosslinking as well as with the T<sub>g</sub> of the polyol from which it was prepared. As the NCO:OH ratio was increased, the major difference in T<sub>g</sub> occurred within the range from 1:1 to 3:1. Similar trends were noted for the viscoelastic properties in both instances. However, it was apparent that the sol fraction contributed significantly to the overall properties of the network, particularly at the high weight fractions. Fracture surface analysis of model substrates (cellulose acetate and cellulose tri-acetate) bonded with a lignin-polyisocyanate resin by Electron Spectroscopy for Chemical Analysis (ESCA) revealed the formation of interfacial bonds on the surface of the cellulose acetate adherend. Furthermore, it was indicated that failure occurred well within the bulk of the cellulose acetate while interfacial failure was apparent for the cellulose tri-acetate model. While mechanical attachment is unquestionably a contributing mechanism, the formation of interfacial bonds should significantly contribute to the performance of bonded joints for this particular adhesive system."],"dc:description.degree":["M.S."],"dc:format.mimetype":["application/pdf"],"dc:identifier.uri":["http://hdl.handle.net/10919/101227"],"dc:language.iso":["en"],"dc:publisher":["Virginia Polytechnic Institute and State University"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:title":["Effect of network structure on lignin-derived polyurethane film properties"],"dc:type":["Thesis"],"dc:type.dcmitype":["Text"],"thesis:degree_discipline":["Forest Products"],"thesis:degree_level":["masters"],"thesis:degree_name":["M.S."],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:35Z"}